Effect of Cooling Rate on Microstructure of Rejuvenated Fe-Ni Based Superalloys

Abstract:

Fe-Ni based superalloys have been widely used in land-base gas turbine application. The turbine blade was in service for 50,000 h at high temperature and stresses. When subjected to long-term exposure at high temperature, the microstructure lost its best mechanical properties due to the microstructural instability. The aim of this research is to understand the effect of cooling rate on gamma (γ) grain size and gamma prime (γ’) particle size, morphology, and its volume fraction in rejuvenated Fe-Ni based superalloys. The alloys were solutionized above the γ’ solvus temperature at 1125 °C for 2 h for homogenization and cooling to room temperature at different cooling rates. The alloys were experienced with furnace cooling, air cooling, oil quenching, and water quenching. Microstructural analyses were investigated. Grain size, morphology, volume fraction of γ’ precipitates were investigated. Preliminary mechanical properties such as microhardness was conducted.

• Periodical: Key Engineering Materials (Volume 856)
• Pages: 76-84
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.856.76
• Online since: August 2020
• Authors: Kittawat Srimark, Panyawat Wangyao, Tanaporn Rojhirunsakool*
• Keywords: Cooling Rate, Microstructure, Rejuvenation, Superalloy

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